Iskanje po katalogu digitalne knjižnice

Opis: Background: City logistics is a critical component of urban economic development, as it optimizes supply chains, enhances customer satisfaction through reliable deliveries, and minimizes environmental impacts in densely populated areas. This field addresses various challenges, including traffic congestion, environmental concerns, noise pollution, and the crucial need for timely deliveries. Routing and scheduling are central to logistics operations, with modern software integrating time windows to meet precise scheduling demands driven by detailed customer requirements and operational efficiencies. Furthermore, advanced vehicle routing models now effectively simulate real-world factors such as traffic congestion, stochastic travel times, and dynamic product demands. Purpose: This paper aims to develop an algorithm that addresses the routing decisions. Our approach extends to the time dimension, considering travel times and customer service times within predefined time windows. Study design/methodology/approach: The proposed algorithm is structured to execute in iterative phases, aiming to optimize key logistical objectives. In order to generate competitive solutions, we seek to minimize the number of vehicles utilized and overall travel costs. The evaluation of solution space was conducted via Simulated Annealing. Findings/conclusions: The performance of the proposed algorithm, evaluated using the Gehring and Homberger benchmark instances for 200 customers, demonstrates its effectiveness. The algorithm successfully meets the target number of vehicles required, and the associated travel costs are on average within 1% of the best solutions reported in the relevant literature. Limitations/future research: Given the ongoing need for timely solutions from decision-makers, future research endeavors will focus on enhancing the computational efficiency of the algorithm. Additionally, incorporating more time-related features, such as stochastic travel times, could further improve the algorithm's real-time applicability.
Ključne besede: city logistics, vehicle routing, simulated annealing, time windows, scheduling
Objavljeno v DKUM: 27.03.2025; Ogledov: 0; Prenosov: 1
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Opis: This paper presents a discrete-event simulation (DES) approach for simulation of distributed energy resources (DER). The DES approach provides means to adapt the energy workloads of the system according to any variations of demands that can occur due to temperature regulation requirements or operational demands. Along with a basic model based on a concrete DER configuration, additional models are presented and analysed in order to demonstrate the adaptability of the DES approach to analyse alternative configurations. The models were tested on historical energy consumption data in order to provide the expected workloads and costs. Models are capable to predict the amount of three different energies and cost for the company based on the inside and outside temperatures.
Ključne besede: cost, discrete-event simulation, distributed energy resources, energy efficiency, hospitals, logistics
Objavljeno v DKUM: 10.03.2025; Ogledov: 0; Prenosov: 8
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Opis: V raziskavi smo si pogledali in raziskali problematiko skladiščenja in skladiščnih procesov v podjetju ZETA Holding na avstrijskem Štajerskem, natančneje v Liebochu, kjer proizvodni proces temelji na projektnih delih, kar pomeni potrebo po veliki prilagodljivosti skladiščenja. Ker se podjetje v zadnjih letih srečuje z rastjo in povečano proizvodnjo, je prišlo do težav in pomanjkanja skladiščnih prostorov ter ustrezne manipulacije. Pomanjkljivosti se odražajo tudi v samih skladiščnih sistemih in načinih skladiščenja. V ta namen smo raziskali različne pristope k reševanju omenjenega problema in trg sodobnih skladiščnih sistemov ter možnosti za njihovo uporabo. Hkrati potrebujemo za sodobne skladiščne sisteme različne vrste manipulativnih sredstev, ki smo jih s pomočjo izkušenj in znanj poiskali pri različnih dobaviteljih ter s tem poiskali najprimernejše izvedbe le-teh. Na koncu smo raziskave združili in poiskali optimizirano rešitev skladiščenja z najprimernejšimi manipulativnimi sredstvi tako, da smo maksimalno izkoristili velikost razpoložljivih skladiščnih prostorov.
Ključne besede: skladiščni proces, skladiščenje, MRP, manipulacijska sredstva
Objavljeno v DKUM: 27.11.2024; Ogledov: 0; Prenosov: 19
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Opis: The outbreak of COVID-19 caused many changes in people's life. One of the most significant is the travel behaviour and transport mode choice. This study focus on the changes that the inhabitants of Vienna made in their travel choices because of the virus. The same research about spatial modelling the transport mode choice of commuters in Vienna was completed in 2019 and is a topic addressed in our previous work. Based on our developed methodology, this article indicates that public transport is not a dominant transport mode choice as it was before the virus outbreak.The main result of this paper is geographically defined areas of application of individual alternatives shown on the final map of modal shift in Vienna, which could provide theoretical support for policy-makers and transportation planners. For the city of Vienna, we found that the area of the city where cars are now used has increased, which certainly has a negative impact on air quality and life in the city. The advantage of the methodology is that it can also be applied to other cities in the world.
Ključne besede: coronavirus, city traffic, urban mobility, transport mode choice, passenger transport, geographical methods, spatial modelling, city logistics, Vienna
Objavljeno v DKUM: 14.10.2024; Ogledov: 0; Prenosov: 21
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Opis: The paper addresses the optimal bus stops allocation in the Laško municipality. The goal is to achieve a cost reduction by proper re-designing of a mandatory pupils' transportation to their schools. The proposed heuristic optimization algorithm relies on data clustering and Monte Carlo simulation. The number of bus stops should be minimal possible that still assure a maximal service area, while keeping the minimal walking distances children have to go from their homes to the nearest bus stop. The working mechanism of the proposed algorithm is explained. The latter is driven by three-dimensional GIS data to take into account as much realistic dynamic properties of terrain as possible. The results show that the proposed algorithm achieves an optimal solution with only 37 optimal bus stops covering 94.6 % of all treated pupils despite the diversity and wideness of municipality, as well as the problematic characteristics of terrains' elevation. The calculated bus stops will represent important guidelines to their actual physical implementation.
Ključne besede: logistics, maximal covering problems, optimization, data clustering, Monte Carlo simulation, geographic information system (GIS), reduction of transportation costs, Laško, Slovenia
Objavljeno v DKUM: 22.08.2024; Ogledov: 35; Prenosov: 13
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